Studies will be continued, the aim of which is to characterize the actions of sex steroids and other hormones upon central nervous function. One area of concentration is the determination of sites of action of hormones upon the hypothalamic rostral preoptic nucleus in evoking a stereotyped sex behavior in male frogs. Particular emphasis will be on the hormonal susceptability of afferent and efferent pathways to and from the organizing center of the behavio in the preoptic nucleus. Continued attention will be made to the subcellular level of metabolism and translocation of sex steroids in the rat brain. Exploration will continue of the nature and properties of a substance other than GnRH in the rat hypothalamus that appears to regulate FSH and LH relase from the pituitary.